Pattern Inspection Device Line Width Correction
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Solution Overview
Problem
Existing pattern inspection apparatuses struggle to accurately detect defects in ultrafine patterns on semiconductor wafers and masks due to line width errors between measurement and reference images, leading to pseudo defects.
Innovation Solution
A pattern inspection apparatus and method that utilize a secondary electron image acquisition mechanism, uniform sizing processing, reference image generation, line-width dependent correction, and comparison circuits to accurately resize and correct line widths, thereby inhibiting line width errors and pseudo defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a reference image is generated from design pattern data without line width correction, then the inspection process is simple and fast, but line width errors occur between measurement and reference images leading to pseudo defects
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing correction amounts for different line width sizes before actual inspection. The correction amounts are determined in advance based on the relationship between line width sizes and observed deviations, then stored for rapid retrieval during inspection. This allows the system to apply corrections without adding significant complexity to the real-time inspection process.
Solution Approach 2:
The patent changes the parameter of line width in the reference image by applying correction amounts based on the actual line width sizes measured in the secondary electron image. Instead of using the nominal design line widths, the system adjusts the reference line widths to match the actual manufactured dimensions, thereby eliminating line width errors and preventing pseudo defects.
2Reliability
If line width correction is applied to all figure patterns, then pseudo defects are reduced, but the processing time and computational load increase
Solution Approach 1:
The patent applies local quality by selectively applying line width correction only to figure patterns where the actual line width differs from the design line width. The system determines the line width of each figure pattern in the secondary electron image, compares it with the design value, and applies correction only when necessary. This approach maintains high defect detection accuracy while minimizing unnecessary processing time for patterns that already match design specifications.
3Measurement precision
If the inspection threshold is set strictly to detect all potential defects, then defect detection sensitivity is high, but the number of pseudo defects increases
Solution Approach 1:
The patent changes the parameter of reference line width by applying correction amounts based on actual measured line widths. This parameter adjustment aligns the reference image with the actual manufactured patterns, allowing the inspection threshold to remain strict without generating pseudo defects. The correction ensures that variations due to manufacturing tolerances are accounted for, so only true defects exceed the threshold.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively reduces line width errors and pseudo defects, enhancing the accuracy of defect detection in ultrafine patterns, thereby improving the yield of LSI manufacturing.
Implementation Method 1
a secondary electron image acquisition mechanism configured to acquire, by using an electron beam, a secondary electron image of a figure pattern formed on a substrate
Data Source
AI summary
According to one aspect of the present invention, a pattern inspection apparatus includes a uniform sizing processing circuit configured to resize a line width of a design pattern being a basis of the figure pattern by using a uniform sizing amount which has been set in advance; a reference image generation circuit configured to generate a reference image corresponding to the secondary electron image by performing image development on data of the design pattern whose line width has been resized; and a line-width dependent correction circuit configured to correct a line width of a figure pattern in the secondary electron image by using a correction amount which has been set in advance depending on a line width size.